The present invention relates to a semiconductor switch utilizing thyristors of the type including an anode, a cathode and a gate or control electrode. A thyristor is a semiconductor switch which permits the switching on of a load current by means of a relatively low control current. In normal thyristors, switching off of the thyristor is effected in that the load current is lowered to below a minimum value, the so-called holding current. However, so-called gate turn-off thyristors are known in which switching off, as well as switching on, are effected via the control current, the control current being directed in the opposite direction for switching off than for switching on of the thyristor. The switch-off behavior of a thyristor is characterized by the turn-off gain which is defined as the ratio of the anode current to the required negative control current. In the presently known embodiments of gate turn-off thyristors, however, a relatively large control current which typically is 10 to 30% of the load current carried by the thyristor in the switched-on state, is required for switching off of the thyristor. Additionally, the transmission losses of gate turn-off thyristors are substantially higher than those of normal thyristors. In particular, a considerable forward voltage drop must be tolerated at very high switch-off amplification. Moreover, in such thyristors the holding current becomes very high. Such devices are described, for example, in the U.S. Pat. No. 3,210,563 issued Oct. 5, 1965 to T. C. T. New and in the Canadian Patent No. 774.273 issued in Dec. 1967 to Moyson et. al.